Aetiology (the causes of PF) is poorly understood (Singh et al, 1997), but is generally considered to be an inflammatory response to repetitive trauma: micro-tears in the plantar fascia (the thick connective tissue that supports the ankle) resulting in foot pain and swelling changed patterns of weight bearing and associated knee and hip pathology.

More than 30 million working days are lost annually due to illness (Health and Safety Commission, 2007), the most common cause being musculoskeletal disorders. This case study examines the impact of PF on work performance, together with the variables used to assess fitness for work.

The client

The client, a postal delivery-man (pseudonym: Paul), was referred to OH by his manager in relation to sickness absence.

Pathology

An exact aetiology of PF is debatable (Roxas, 2005). Contributory factors include excessive weight, anatomical variations, poor biomechanics, occupationally-related activities and inadequate footwear (Roxas, 2005), however there is a lack of supporting empirical evidence relating to many of these (Irving et al, 2007). PF may also be due to lack of cushioning, increased stretching in flat feet, and heel spurs – growths of bone on the underside of the foot in the area of the heel bone) (DeMaio et al, 1993).

It is thought that PF originates from repetitive micro-trauma to the plantar fascia at its origin on the calcaneus (Singh, 2006), and associated inflammatory processes. However, Lemont et al (2003) suggest that some presentations are more degenerative than inflammatory.

The plantar fascia, a band of fibrous connective tissue originating from the medial calcaneal tuberosity, fans out inserting into the plantar plates of the metatarso-phalangeal joints and flexor tendon sheaths (Singh et al, 1997).

After the heel strikes a surface during walking, the tibia turns inward and the foot pronates (moves in a rotational movement) allowing flattening of the foot and stretching the plantar fascia. Where pre-disposing factors exist, repetitive traction on this tissue results in micro-tears (Singh et al, 1997). An acute inflammatory response ensues involving complex microvascular and cellular events resulting from chemical mediator release (Woolf, 2000).

Paul’s pre-disposing factors included obesity, poor biomechanics due to flat feet, together with occupational exposures of frequent walking over uneven surfaces in inadequate footwear. Pain prevented Paul putting his heel to the floor, necessitating an adjusted gait and eventually resulting in walking difficulties.

Pain results from a complex chain of actions including:

Inflammatory processes – increased tissue tension (Woolf, 2000) vasodilation increased capillary permeability (the process in which the walls of capillaries allow substances such as oxygen, glucose and water to pass through them) and activation of pain receptors (O’Connor & Jones, 2002).

Rest and foot elevation reduced the potential for further trauma induced by walking and the pressures from the gravitational effects of blood flow and oedema.

Assessment of fitness to work

The OH nurse needs sound understanding of cause and effect of employees’ health status, and understanding of job role and work environment to restore good health and work performance. They have a key role in assessing fitness for work (Black, 2008) and recommending a return-to-work strategy. Early interventions (Black, 2008a HSE, 2005aHSE, 2005b) and the use of biopsychosocial models rate highly among these principles (Black, 2008a Smith, 2006Burton & Waddell, 2004).

This framework demonstrates the need for evolution in OH practice within the changing world of work (Smith, 2006).

Personal aspects

Assessment of Paul’s personal aspects included biopsychosocial characteristics (Burton &Waddell, 2004) – for example, body mass index, the past and current health and social history impacting on his condition. Paul’s physical abilities and stamina for conducting the job were assessed through observation and history taking.

A full assessment of Paul’s foot at pre-employment might have led to the identification of his flat feet and the recommendation that he be supplied with orthotic insoles and supportive shoes to reduce his risks of developing PF.

Work characteristics

Paul’s work involves loading mail into six 16kg shoulder pouches, dropping off five pouches at ‘drop locations’ by car, and delivering the mail in the sixth pouch door-to-door. He works seven-and-a-half hours a day, which is mostly spent standing or walking.

Assessment of work characteristics is conducted within the history-taking process. While the employee may be the best judge of necessary characteristics, their own views may vary from that of managers or from reality. The OH nurse must have a full understanding of the client’s role, assisted by job descriptions and a workplace assessment.

An immediate return to full duties would have been detrimental to Paul’s recovery. Recommendations made by the OH nurse over a defined period included alternative indoor sedentary duties and adjusted hours.

Work environment

Assessment of the work environment encompasses multiple variables including physical (Worth, 2000) and ergonomic (Kroemer & Grandjean, 2003), economic and sociological factors, which could include workplace culture, facilities, policies and training.

Paul works in all weather, often walking over uneven ground, up and down steps, and frequently negotiating obstacles while carrying a heavy load. There is some indication that his shoes were inappropriate given the intensity, type of walking and his individual biomechanics (Merriman & Turner, 2006). This was recorded in the report to management, since this might have been a contributory factor regarding his condition.

Legal aspects

Employers have obligations relating to workers’ health (Kloss, 2005). The legal position emphasises the need for comprehensive assessment of fitness to work as undertaken by OH practitioners, on which employers are entitled to rely (Murugiah et al, 2002).

The OHN’s assessment of Paul took account of the employer’s duty of care, under the Health and Safety at Work Act and a legal requirement to risk assess (Health and Safety Executive, 2002) together with his requirement for suitable work equipment, meaning appropriate shoes, as well as a variety of other legislative requirements that might impact on his work (eg Workplace Health Safety and Welfare 1992 & Manual Handling Operations Regulations 1992).

Summary and recommendations

The OHN recommended a physiotherapy referral, period of indoor, predominantly sedentary, duties with adapted hours and the purchase of orthotic insoles. Paul was assessed throughout a specified phased return – eventually resuming full duties.

Assessment of fitness to work involves integrating a range of knowledge and skills requiring an appreciation of patho-physiological changes and comprehensive recognition of legislation, organisational processes and culture.

Anita Churchouse won an award for being the London South Bank University graduate with the top mark in the 2007-08 final examination. This is an edited version of her original paper.

References

Black, C. (2008,a) Working for a healthier tomorrow: Review of the health of Britain’s working age population. London: TSO

Black, C. (2008,b) Summary of evidence submitted: Review of the health of Britain’s working age population. London: TSO

Micro-tears within the plantar fascia are exacerbated by the release of chemical mediators, predominantly from the membrane phospholipids of damaged cells, and changes in membrane permeability associated with alteration in the adenosine tri-phosphate (ATP) transport system (Marieb, 2006).

Oedema (swelling) follows a partial failure of the sodium pump, which transports molecules across membranes, and disruption to active and passive membrane transport systems become disturbed. Numerous complex chemical mediators within damaged tissue interact and cause the following responses (O’Connor & Jones, 2002):

Damaged tissue results in an influx of calcium and activation of phospholipase A2 and release of arachnidonic acid (Woolf, 2000), the starting point of lipo-oxygenase and cyclo-oxygenase pathways.

Sensitisation resulting from these mediators is characterised by a lowering of the pain-inducing threshold (Levine & Taiwo, 1994 & Wang et al, 2005). Inflammatory mediators are also thought to exert prolonged pain continuing long after the initial injurious impulse has disappeared (Sofaer, 1998).

Client profile

Sex: Male

Age: 28

Exercise: Occasionally plays football

Employment: Five years as a delivery postman.

Tasks: Sorting mail, walking a daily delivery round (three to four hours) on hard, uneven walking surfaces carrying a heavy load. Pain began in left heel. Continued working by gait adjustment but unable to complete his delivery. The heel was tender to touch, worse first thing in the morning and later in the day, particularly when bearing weight. OH referral followed a five-week absence.